Outline around a group of sprites in 2D platformer

Dear all,

I’m creating a simple game using basic single color rectangles to build my 2D platformer level.
I want to create a simple visual style that has border / outline around every object.
Can this be done easily? It has to be done for a lot of sprites so i don’t know if dynamically creating the border is efficient?

This is part of what i have: it is composed of several scaled/rotated blocks


and this is what i want to achieve

Find an editor with the possibility to add borders to sprites and tune different variations of sprites with borders and connect them like lego.

use shaders, follow this tutorial